LangChain Data Handling — Loaders and Splitters (Python)

Overview

You have a RAG system over a Python docs site. A user asks "what does trim_messages do?" and the retriever returns this chunk:

### `trim_messages(strategy="last", include_system=True)`

Trim a message history to fit a token budget. The newest messages are kept;
older messages are dropped. Pass `include_system=True` to preserve the system

...and that's it. The chunk ends there. The code example showing the function body — the actual thing the user wanted — is in a different chunk, retrieved with a lower similarity score and dropped before the LLM sees it. The model then hallucinates the function's behavior from the signature alone.